When should you worry about blood in stool

Cancer Colon Cancer

Colon and rectal cancers do not usually produce symptoms in the early stages of disease. As the tumor grows, symptoms will depend on the location of the primary tumor within the intestine.

Patients with colon cancer or rectal cancer may experience one or multiple symptoms. These may include the following:

Blood in the Stool

You may notice obvious blood the stool, or darker colored bowel movements, which may indicate that there is bleeding within the intestinal tract or rectum. Sometimes bleeding may be present but not visible. This is called occult (hidden) blood and may not be discovered until a blood test indicates a low red blood cell count.

Rectal Bleeding

Bright red blood in the stool typically indicates that there is bleeding in the rectum or colon, which may be a sign of colon or rectal cancer. Rectal bleeding can also be caused by hemorrhoids. Typically, patients with hemorrhoids experience symptoms that come and go with flare-ups, whereas rectal bleeding caused by cancer usually continues or worsens and is more likely to be accompanied by pain.

Changes in Bowel Habits

Changes in bowel habits that can indicate colon or rectal cancer include the following:

  • New-onset constipation or diarrhea

  • Changes in frequency or size and caliber of bowel movements

  • A bowel that doesn’t seem to empty completely

  • Stool that is narrower than normal (even as thin as a pencil)

Occasional bowel changes can be caused by a dietary change, disagreeable food or a viral/bacterial infection. However, if you are experiencing something new and unexplained—and it lasts more than a couple of days—see your doctor.

5 Things Your Poop Can Tell You About Your Health

Ever curious what bowel changes could signal about your health? Poop may be a gross topic that no one likes to talk about, but taking a quick peek before you flush may give you clues about your health.

Abdominal Pain and Bloating

Stomach bloating, distention, cramps or pain in the abdominal or bowel region can be symptoms of colon or rectal cancer. These are common issues that can also be caused by a number of conditions, including diet-related gastrointestinal distress, Crohn’s disease or ulcerative colitis. See your doctor if you experience frequent abdominal pain and bloating that does not have an obvious cause.

Nausea and Vomiting

Nausea and vomiting can occur if a colon or rectal tumor is obstructing the bowel and inhibiting the passage of liquid or solid waste or gas. Bowel blockage can also be accompanied by painful abdominal cramps, bloating and constipation.

Nausea and vomiting are symptoms of a range of conditions, which may be benign or serious. If you experience persistent nausea, signs of dehydration or vomiting that lasts for more than 24 hours, seek immediate medical treatment.

Anemia

Anemia is a blood disorder characterized by a deficiency of red blood cells or hemoglobin. In patients with colon or rectal cancer, intestinal bleeding may cause anemia. Depending on the location of the bleeding within the colon, anemia can be the first sign that blood loss is occurring.

Common symptoms of anemia include skin pallor (paleness), increased heart rate, fatigue, dizziness and irregular menstruation.

Unexplained Weight Loss, Loss of Appetite and Feeling Weak

Losing weight, losing your appetite or feeling weak are all possible signs of colon or rectal cancer along with many other unrelated conditions. In patients with colon or rectal cancer, these symptoms are usually related. Persistent diarrhea can cause weight loss. Stomach pain and nausea can reduce your appetite so that you don’t consume enough food to maintain your weight. All these issues, as well as anemia, can lead to weakness.

Pelvic Pain

Pain in the pelvic area is not common in patients with colon or rectal cancer. If it occurs, it may indicate that the cancer has spread to the pelvic area.

On this page

  • What does blood in stools look like?
  • What causes blood in stools?
  • When should I see a doctor?
  • What tests are used to find the cause of blood in stools?
  • How is blood in stools treated?
  • Related information on Australian websites

After you have used the toilet, you might see blood in your poo (stool), spotting on the toilet paper or drops in the toilet bowl. Many people dismiss this as nothing or they are too embarrassed to seek help. But blood in your stool can indicate a range of problems, some of which are very serious.

If you have blood in your stools and you feel faint, dizzy or light-headed, this may be an emergency. Go to the nearest emergency department as soon as possible or call triple zero (000) and ask for an ambulance.

Go to the emergency department if you have heavy rectal bleeding and also have bad stomach pains.

What does blood in stools look like?

Blood from your stool could look bright red, or it might be dark red or black.

How the blood looks depends on where it is coming from.

Spots of red blood on the toilet paper, drops in the toilet bowl, blood on the surface of your stool or in your underwear indicate the bleeding is coming from the anus or lower rectum.

If the blood is mixed in with your stool, this suggests bleeding might be from higher up in the bowel.

If your stools are black and like tar, and they smell bad, this is also probably because the blood is coming from higher up in the bowel.

What causes blood in stools?

Blood in your stool can be caused by many different things. These include:

  • haemorrhoids
  • anal fissures, which are small painful cracks in the anus
  • bowel infections
  • bowel cancer
  • colorectal polyps, which are small growths that can become cancerous
  • inflammatory bowel disease (Crohn's disease and ulcerative colitis)
  • diverticular disease
  • fistula (an abnormal opening in the rectum or anus)
  • prolapse (when part of the rectum sticks out of the anus)
  • an injury

CHECK YOUR SYMPTOMS — Use the Blood in stool and rectal problems Symptom Checker and find out if you need to seek medical help.

When should I see a doctor?

If you have any blood in your stool or bleeding from the anus, make sure you get it checked out by a doctor.

As well as blood in your stool, you might have other symptoms that could indicate something more serious is going on.

If you have blood in your stool and you feel faint, dizzy or light-headed, this may be an emergency. Go to the nearest emergency department as soon as possible or call triple zero (000) and ask for an ambulance.

If you are losing weight and have blood in your stool, this suggests an illness that needs treatment. See your doctor as soon as possible.

If you received some trauma to the area, you might have an injury or a foreign object in the area. Seek an examination from your doctor as soon as possible.

FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

ASK YOUR DOCTOR — Preparing for an appointment? Use the Question Builder for general tips on what to ask your GP or specialist.

What tests are used to find the cause of blood in stools?

Your doctor will talk to you, examine you, and should arrange some tests to investigate the cause. The doctor will choose the right test for you based on your age, symptoms and medical history. Possible tests include:

  • rectal examination — your doctor or nurse looks and feels around your rectum, anal canal and nearby organs, such as the prostate and bladder
  • anoscopy — a procedure where your doctor will use a camera in a tube to view the last 5cm of your anus and lower rectum
  • sigmoidoscopy — a procedure where your doctor uses a camera to check inside your rectum and most of your lower large intestine (‘sigmoid colon’)
  • colonoscopy — a physician uses a camera that sits within a tube to examine your entire colon
  • gastroscopy — a tube is inserted through the mouth to look at the oesophagus, stomach and first part of the small intestine

Some of these tests are done under sedation and anaesthetic. Ask your doctor for more information.

How is blood in stools treated?

The right treatment for blood in your stool depends on what is causing the problem.

If it is caused by haemorrhoids or an anal fissure, the treatment could be to make changes to your lifestyle or diet. Sometimes surgery is needed.

If the bleeding is due to a haemorrhage, for example if you have diverticular disease, you may need emergency surgery.

Polyps may be removed during a colonoscopy. If you have bowel cancer, you might need more urgent and invasive treatment such as surgery, chemotherapy, radiotherapy or other treatments.

When should I be concerned about blood in my stool?

Stools with blood can be caused by many different conditions. If you are experiencing bloody stools or bleeding from a bowel movement, you may need to see a doctor. Seek immediate medical attention if you are experiencing fever, excessive weakness, vomiting, or seeing large amounts of blood in your stool.

What does cancerous blood in stool look like?

Blood from higher up in the bowel doesn't look bright red. It goes dark red or black and can make your poo look like tar. This type of bleeding can be a sign of cancer higher up the bowel.

Is bright red blood in stool serious?

If you notice blood in the stool, it warrants a call to your physician. Red blood in the stool and rectal bleeding are associated with many diseases and conditions of the digestive tract, including colon and rectal cancer, diverticular disease, inflammatory bowel disease (IBD), among others.

How much blood is too much in stool?

No amount of blood in the stool is normal, but some causes may be more dangerous than others. Sometimes there is blood in such small amounts that it can't be seen with the eye. In these cases, it must be identified with a test called a fecal occult test.